The present invention relates to a system for filtering and/or treating blood and more specifically to a system which is capable of filtering blood from bone marrow and/or altering a property thereof in order to treat a disorder or disease.
Congestive heart failure (CHF) is a condition in which the blood pumping function of the heart is inadequate to meet the needs of body tissue. CHF is one of the most common causes of hospitalization and mortality in Western society.
CHF results from a weakening or stiffening of the heart muscle most commonly caused by myocardial ischemia (due to, for example, myocardial infarction) or cardiomyopathy (e.g. myocarditis, amyloidosis). Such weakening or stiffening leads to reduced cardiac output, an increase in cardiac filling pressures, and fluid accumulation. Reduced cardiac output can lead to diminished kidney function and a result to retention of fluid in body tissue. The lungs and liver may also become congested with fluid, thereby impairing the normal function of these organs. In addition, the intestines may become less efficient in absorbing nutrients and medicines. CHF may result in refractory pulmonary edema which may be treated by IV diuresis or ultrafiltration via hemofiltration or dialysis. Over time, untreated CHF will negatively affect virtually every organ in the body.
End-Stage Renal Disease (ESRD) occurs when the kidneys are no longer able to function at a level that is necessary for day-to-day life, up to the point where kidney function is less than about 10% of a normal, disease-free kidney. The most common cause of ESRD is diabetes. Symptoms of ESRD can include, for example, unintentional weight loss, nausea or vomiting, general ill feeling, fatigue, headache, decreased urine output, easy bruising or bleeding, blood in the vomit or stools, elevated blood urea nitrogen (BUN) levels and decreased creatinine clearance.
Dialysis and/or ultrafiltration are performed on individuals suffering from ESRD or CHF-related fluid overload. The process involves removing waste substances and fluid from the blood that are normally eliminated by the kidneys. Dialysis may also be used in individuals exposed to toxic substances in order to prevent renal failure from occurring.
There are two types of dialysis that may be performed: hemodialysis and peritoneal dialysis.
Hemodialysis involves fluid removal through ultrafiltration, causing free water and some dissolved solutes to move across the membrane along a created pressure gradient. Hemodialysis also utilizes a counter current flow of dialysate which performs adjustments of solutes by creating concentration gradients across the membrane at a maximum and increases the efficiency of the dialysis. The blood is taken by a special type of access, called an arteriovenous (AV) fistula, which is placed surgically, usually in the arm. After access has been established, the blood drains though a large hemodialysis machine which bathes the hemofiltration cartridge in a special dialysate solution that adjusts solute concentration and removes waste substances and fluid. The “clean” blood is then returned to the bloodstream. Hemodialysis is usually performed three times a week with each treatment lasting from 3 to 5 or more hours. Because proper maintenance of hemodialysis equipment (e.g. membranes, pumps) is critical, hemodialysis sessions are often performed at a treatment center. Possible complications of hemodialysis can include muscle cramps and low blood pressure caused by removing too much fluid and/or removing fluid too rapidly. The AV fistula often undergoes thrombosis which limits the use of the fistula and may require surgical interventions for clearing and or replacement of the fistula.
Peritoneal dialysis uses the peritoneal membrane to filter the blood. Peritoneal dialysis is performed by surgically placing a special, soft, hollow tube into the lower abdomen near the navel. A mixture of minerals and sugar dissolved in water, called dialysate solution, is instilled into the peritoneal cavity and is left in the abdomen for a designated period of time in which the dialysate fluid absorbs the waste products, toxins and extra water through the peritoneum membranes. After several hours, the used solution containing the wastes from the blood is drained from the abdomen through the tube. Then the abdomen is refilled with fresh dialysis solution, and the cycle is repeated. The process of draining and refilling is called an exchange. Patients usually undergo four to six exchanges of the dialysis solution per day. An infection of the peritoneum, or peritonitis, is the most common problem of peritoneal dialysis.
Although dialysis is a common procedure it suffers from several disadvantages, including fluids balance impairment, the need of special diet, high blood pressure, psychological problems because of the change in the life style due the need to go to the dialysis treatment several times a week for several hours each time. Due to the increasing numbers of patients requiring dialysis, this introduces a tremendous burden on the healthcare system.
Several attempts have been made to devise systems which overcome at least some of the aforementioned limitations of dialysis devices. U.S. Pat. No. 5,037,385 and Ser. No. 10/922,478 disclose implantable peritoneal dialysis devices. The aforementioned system described includes an implantable peritoneourinary pump system and an implantable dialysate infusion system. When in use, the device has a semi-permeable reservoir implanted in the peritoneal cavity. The reservoir receives blood waste and drains through one or more conduits via a pump to the biological bladder, which is a complicated arrangement.
U.S. Pat. No. 5,902,336 describes another implantable system which employs an ultrafiltration device for removing low to medium molecular weight solutes and fluids from the blood of a patient experiencing renal failure. In this system the fluid flows between the patient's vascular system, through an access to the artery and/or vein, and the patient's bladder or urethra. As such, this system requires surgical attachment of a metal or hard plastic device, to a soft biological tissue (artery or vein), a procedure which often results in undesirable side effects such as vessel shearing/tearing, clotting, fibrosis, infection and thrombosis.
While reducing the present invention to practice, the present inventors have devised a system which is designed for ultrafiltration and/or treatment of bone marrow blood while overcoming limitations of prior art devices.